#particles-js {
  width: 100%;
  height: 100%;
  position: fixed;  
  z-index: 1;
  margin-left: auto;
  margin-right: auto;
}
::-webkit-scrollbar {
/*隐藏滚轮*/
display: none;
}
@media screen and (min-width: 768px) {
    #student {
        width: 70%;
        margin: 0 auto;
    }
}

